Spring loaded fixation element insertion device

ABSTRACT

The invention relates to a device for attaching fixation elements to bone, having a longitudinal member with a channel extending therein adapted for receiving at least one fixation element. A shaft extends within the channel and is positioned coaxially within at least a portion of the longitudinal member and at least a portion of the shaft is retained within the longitudinal member and a distal end of the shaft is configured and adapted to contact at least a portion of the fixation element received within the longitudinal member. A spring is positioned adjacent the shaft for resiliently biasing the shaft in an axial direction and the shaft is moveable with respect to the longitudinal member to drive the fixation element into bone.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Priority of Provisional Application No. 60/330,977, filed on Nov.5, 2001 is claimed under 35 U.S.C. §119 and priority of U.S. patentapplication Ser. No. 09/866,841, filed on May 30, 2001 and PCTApplication No. PCT/US02/16656, filed on May 28, 2002 is claimed under35 U.S.C. §120, the entire contents of which are incorporated byreference.

FIELD OF THE INVENTION

[0002] The present invention relates to a device for the storage anddispensing of osteosynthetic fixation elements, and in particular to adevice for attaching fixation elements to bone.

BACKGROUND OF INVENTION

[0003] In the surgical treatment of fractures in the maxillofacial area,as well as fractures of the foot and hand, a trend toward preferringever-smaller implants can clearly be noted. The reason for this is thegenerally increased understanding of the biomechanical bases ofosteosynthesis. In the field of treating maxillofacial fractures, moreattention can be paid to the cosmetic results of osteosynthesis, thanksto the miniaturization of implants. In the field of hand surgery,restrictions on movement in the area of the fingers can be avoided. Inthis regard, smaller osteosynthetic implants in the fingers can beplaced under the tendons. In the case of an implant with a largecross-section, the tendons need no longer be extended to their fulllength.

[0004] The dimensions of some smaller implants (screws, plates andtacks) are in the range of about 0.8 mm to about 2.0 mm. Problems in thearea of packaging, storage and manipulation during surgery arise due tothis miniaturization. Handling in the operating room, particularly inthe maxillofacial area, has proved difficult. Depending on the degree ofseverity of the fracture or correction, up to 40 bone fixation elements,such as tacks or screws, may be required. These screws must be takenindividually by the operating room nurse from a so-called screw rack,checked for length, placed on a screwdriver and given to the surgeon.The surgeon must, in turn, insert them through the osteosynthesis plateinto pre-drilled screw holes. During the transfer of the screw and theattempted insertion of the screw, it often falls off the screwdriver,into the wound or onto the operating room floor. The attempt to find alost screw is often excessively time-consuming, given their dimensionsand extends the time spent in surgery. The frequent loss of screws inthe operating room, and during packing and sterilization, causesunnecessary costs for the hospital. Thus, it is desirable to have asimple device that can be operated with one hand, thereby freeing theoperator's other hand to align the fixation element or perform othertasks

[0005] An additional problem in dealing with mini-screws arises duringtheir implantation. After the surgeon has selected the osteosynthesisplate proper for the fracture in question, a plate is positioned overthe fracture. A hole is then drilled for the screw (0.5-1.5 mm diameter)through one of the plate holes. Commonly, problems arise in controllingthe amount of force applied during the insertion of the screw and ortack. For example, if a surgeon is required to insert a screw or tackwith manual force, the manula force could be transmitted to thesurrounding bone, which could bend thin and/or flexible bone in youngpatients.

[0006] Also, problems such as surgical gloves tearing or hand pinchingcan arise if the insertion device has parts that move externally duringthe firing of the device. Thus, a need exists for an insertion devicethat minimizes the manual force exertion required and to minimize thegross forces applied to the surrounding bone during insertion.

SUMMARY OF INVENTION

[0007] The present invention relates to a device for attaching fixationelements to bone, including a longitudinal member extending along alongitudinal axis from a proximal end to a distal end and having achannel extending therein adapted for receiving at least one fixationelement. A shaft extends within the channel and is positioned coaxiallywithin at least a portion of the longitudinal member and at least aportion of the shaft is retained within the longitudinal member and adistal end configured and adapted to contact at least a portion of thefixation element received within the longitudinal member. A spring ispositioned adjacent the shaft for resiliently biasing the shaft in anaxial direction and the shaft is moveable with respect to thelongitudinal member to drive the fixation element into bone.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a partially transparent elevated view of one embodimentof an insertion device according to the present invention;

[0009]FIG. 2 is an elevated view of a fixation element for use with theinsertion device of FIG. 1;

[0010] FIGS. 3-4 illustrate the placement of a fixation element within apre-drilled hole in bone;

[0011]FIG. 5 is a partially transparent elevated view of anotherembodiment of an insertion device;

[0012]FIG. 6 a partial elevated view of the device of FIG. 5;

[0013]FIG. 7 is a partially transparent elevated view of anotherembodiment of an insertion device;

[0014]FIG. 8 is a cross-sectional view of the embodiment of FIG. 7;

[0015]FIG. 9 is a partial cross-sectional view of a portion A of thedevice of FIG. 8;

[0016]FIG. 10 is an elevated view of another embodiment of an insertiondevice; and

[0017] FIG.11 is an elevated view of a cam member of the device of FIG.10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Referring to FIG. 1, a preferred fixation element insertiondevice 10 according to the present invention generally includes alongitudinal member extending along a longitudinal axis 12 from aproximal end 14 to a distal end 16 and having a channel 18 extendingtherein. The insertion device is preferably used to drive anosteosynthetic fixation element, such as a resorbable tack, into bonetissue. Channel 18 is configured and dimensioned to receive at least onefixation element for storage, transport, dispensing, and or insertioninto bone.

[0019] Referring to FIG. 2, one preferred fixation element compatiblewith insertion device 10 comprises a tack 20 having a shaft 22 integralwith a head 24 at a proximal end thereof. The distal end of shaft 22 hasa conical nose 26 to facilitate the insertion of tack 20 into bonetissue. A plurality of circular ribs 28 extend radially from theexterior of shaft 22 to prevent the removal of the tack from the bonetissue after it has been inserted. Head 24 has an outer diameter greaterthan the diameter of shaft 22 and contacts or rests against the bone orbone plate when the tack is inserted into bone tissue. In the preferredembodiment, the tack is made from a resorbable material so that itremains in the bone tissue temporarily and is absorbed by the body. Inalternate embodiments, tack 20 can have numerously differentconfigurations and dimensions. Also, different types of fixationelements altogether can be used with insertion device 10. For example,biocompatible screws, nails, anchors, rivets, or other similar implantscan also be inserted using insertion device 10.

[0020] Referring again to FIG. 1, insertion device 10 has a handle 30 atthe proximal end that is configured to conform to the shape of aperson's hand or palm for easily gripping the device and an applicatorextension 32 for holding and dispensing the fixation element. A centralchannel 70 extends within handle 30 and through extension 32 and is incommunication with channel 18 at distal end 16. Channel 18 generallycomprises a socket defined at the distal end 16 and an elongateapplicator extension 32 extends between distal end 16 and handle 30.Extension 32 can be a unitary extension or can include multiple parts.Socket or channel 18 fits about the proximal end of fixation element 20to hold element 20 in insertion device 10 by an interference or frictionfit. In the embodiment of FIG. 1, an individual tack 20 can be held atdistal end 16 and head 24 of tack 20 is preferably held within thesocket or channel 18 while the shaft 22 of tack 20 projects outsidethereof, as shown in FIG. 3. At the distal end of extension 32 is apronged tip 34 for retaining a fixation element. Pronged tip 34 isgenerally flexible and when the distal end of extension 32 is pressed,the prongs 34 of sleeve 32 flex around the head of a fixation element topick up and retain the element. In this way, it is possible to pick up arelatively small fixation element in a simple, single action.

[0021] A shaft member 36 and a firing spring 38 are housed withincentral channel 40. Shaft member 36 extends longitudinally within handle30 and extension 32 and is preferably moveable along axis 12 withrespect to handle 30 and extension 32. Firing spring 38 is positioned atthe proximal end of handle 30 and is compressible between a forceadjustment dial 39 at proximal end 14 and a proximal end of shaft member36, biasing shaft member 36 in the distal direction. Shaft 36 isgenerally cylindrical and includes a base portion 42 that slidinglyengages the interior of channel 40 within handle 30, a mid-section 44having a smaller diameter than base portion 42, and a tip portion 46having a smaller diameter than mid-section 44. A first shoulder 43 ispositioned at the transition of base portion 42 and mid-section 44 and asecond shoulder 45 is positioned at the transition of mid-section 44 andtip portion 46.

[0022] Shaft 36 is moveable from a loaded position (shown in FIG. 1) toan unloaded position for inserting a fixation element into bone. Anactivation button 48 extends within channel 40 for activating themovement of shaft 36 from a loaded position to an unloaded position.Button 48 is positioned along a portion of handle 30 and partiallyextends within channel 40 for engaging shaft 36. Referring to FIG. 1,when shaft 36 is in the loaded position ledge 49 at the proximal end ofbutton 48 engages second shoulder 45 preventing shaft 36 from moving inthe distal direction or to the unloaded position. When button 48 isdepressed by an operator, ledge 49 is moved out of engagement withshoulder 45, thereby permitting shaft 36 to move in the distal directionunder the force exerted by firing spring 38 on shaft 36. As a result,tip portion 46 of shaft 36 is advanced in the distal direction to forcefixation element out of extension 32 and shaft 36 is moved to anunloaded position.

[0023] In a preferred embodiment, button 48 is pivotably positionedabout a pin 47 and the distal portion of button 48 is biased radiallyoutward by a spring 50 so that ledge 49 at the proximal portion ofbutton 48 is biased inward toward engagement with shoulder 82. In thisregard, a collar 51 is preferably positioned within handle 30 forengaging spring 50 in the radial direction and permitting mid-section 44of shaft 36 to slide therethrough without engaging spring 51. Whenbutton 48 is depressed, ledge 49 is pivoted radially outward and out ofengagement with shoulder. In alternate embodiments, different buttonassemblies or triggering mechanisms can be used.

[0024] In a preferred embodiment, a thumb slide 52 is positioned along aportion of handle 30 opposite activation button 48 and is moveable inthe longitudinal direction for moving shaft 36 from an unloaded to aloaded position. Thumb slide 52 partially extends within channel 40 forengaging shaft 36 and moving shaft 36 in the longitudinal direction. Inan unloaded position, shoulder 45 engages an inner ledge 53 of thumbslide 52 and when thumb slide 52 is moved in the proximal direction byan operator, shaft 36 is also retracted. To move shaft 36 to the loadedposition, thumb slide 52 is moved in the proximal direction untilshoulder 45 slides beyond ledge 49 of button 48 and ledge 49 engagesshoulder 45, thereby locking shaft 36 in the loaded position. This shaftretraction will also compress firing spring 38. In a preferredembodiment, a spring 54 is housed within handle 30 and biases thumbslide 52 in the distal direction and once shaft 36 is in the loadedposition, the thumb slide is released and returns to its restingposition. Once shaft 36 is again in the loaded position, another tackcan be inserted into the extension 32.

[0025] Referring to FIGS. 3-4, once the insertion device is loaded, theinsertion device can be used to fasten a plate 56 or other device to abone 57. In operation, a hole 58 is pre-drilled in the bone tissue atthe desired insertion location and the insertion device 10 is placedadjacent the insertion location and the tack is aligned with hole 42.The activation button 48 is depressed to release shaft 36, and shaft 36is driven in the distal direction by the force of firing spring 38thereby driving tack 20 into the bone tissue. As shown in FIG. 4, oncetack 20 is inserted into bone, insertion device 10 is withdrawn from theinsertion location and tack 20 is separated from channel 18. When theinsertion device 10 is withdrawn, the forces holding shaft 22 of tack 20to bone 57 are greater than the forces of the interference fit betweenhead 24 and channel 18 so that head 24 of tack 20 is separated fromdistal end 16, leaving tack 20 secured to the bone. The device 10 canthen be reloaded by moving the thumb slide in the proximal direction asexplained above and inserting slightly smaller external dimensions thanthe internal dimensions of cover 78 so that the proximal end of sleeve82 can be inserted into the distal end of cover 78 and sleeve 82 canmove in the axial direction with respect to cover 78. As best seen inFIG. 9, sleeve 82 can include prongs that interlock with ridges on theinterior of cover 78 so that when sleeve 82 is inserted into cover 78,sleeve 82 is not inadvertently removed from cover 78 in the distaldirection. In a preferred embodiment, sleeve 82 has prongs 84 that areflexible and are collapsible or bendable into the interior of sleeve 82so that sleeve 82 can be removed from cover 78 for cleaning,disassembly, or replacement. Prongs 84 are biased radially outwardly sothat sleeve 82 can be easily reattached by simply pushing the sleeveinto the cover in the proximal direction. The distal end of sleeve 82preferably has a pronged tip similar to that described previously forretaining a fixation element.

[0026] A central channel 90 extends within handle 72 and throughextension 74 and houses a firing spring 91 and a shaft member 92 similarto the embodiment of FIG. 1. Firing spring 91 is biased between forceadjustment dial 93 and the proximal end of shaft 92. Adjustment dial 93includes a knob 100 with internal threading that engages an externallythreaded adjustment slider 102 that is slidably housed within channel90. When knob 100 is rotated, adjustment slider 102 slidably moveswithin channel 90 and compresses or decompresses spring 91 for adjustingthe amount of force that is exerted on shaft 92 and consequently thetack during insertion. A pair of knob retaining screws 104 extendradially inward from the exterior of handle 72 and engage a circulargroove in knob 100 for retaining knob 100 in the proximal end of handle72. A guide screw 106 extends inward from handle 72 and engage alongitudinal groove in adjustment slider 102 to prevent the slider fromrotating.

[0027] Shaft 92 extends longitudinally within handle 72 and is generallyidentical to shaft 36 described above, moving between a loaded and anunloaded position. Shaft 92 includes a base portion 94, a mid-section 96having a smaller diameter than base portion 94, and a tip portion 98having a smaller diameter than mid-section 96. A first shoulder 95 ispositioned at the transition of base portion 95 and mid-section 96 and asecond shoulder 97 is positioned at the transition of mid-section 96 andtip portion 98. Device 70 includes an activation button 108 similar tobutton 48 described above for facilitating movement of shaft 92 from theloaded to the unloaded position in the same fashion as described withrespect to the embodiment of FIG. 1. To move shaft 92 from the unloadedto the loaded position, holding sleeve 82 and tip portion 98 of shaft 92is retracted in the proximal direction until shoulder 97 of shaft 92slides beyond button 108 and the button engages shoulder 97, therebylocking shaft 92 in the loaded position in a similar fashion to button48 described above. Also, insertion device 70 preferably has a spring 80housed within spring cover 78 that biases holding sleeve 82 in thedistal direction and once shaft 92 is in the loaded position, theholding sleeve is released and returns to its resting position. In thisway, shaft 92 can be easily moved from the unloaded to the loadedposition, by depressing device 70 in the distal direction against asolid object, such as a table or a surgeons hand. In all other respects,the method of operation or use of device 70 is similar to the methoddescribed above with respect to device 10.

[0028] Referring to FIGS. 10-11, another embodiment of an insertiondevice 110 is shown that has yet another alternative loading mechanism.In all other respects, device 110 is similar to device 70 describedpreviously. Insertion device 110 has a cam 112 for moving shaft 92 fromthe unloaded to the loaded position. In this embodiment, shaft 92 haspins 114 extending outwardly therefrom that engage an internal ramp 116within cam 112 and when cam 112 is rotated pins 114 slide along ramp1116 in the proximal direction and thereby move shaft 92 in the proximaldirection and shaft 92 is retracted until shoulder 97 of shaft 92 slidesbeyond button 108 and the button engages shoulder 97, thereby lockingshaft 92 in the loaded position in a similar fashion to button 48described above. After shaft 92 is locked into the loaded position, cam112 is rotated to provide clearance for pins 114 to move in the distaldirection during the unloading or firing movement of shaft 92.

[0029] While it is apparent that the illustrative embodiments of theinvention herein disclosed fulfill the objectives stated above, it willbe appreciated that numerous modifications and other embodiments may bedevised by those skilled in the art. Therefore, it will be understoodthat the appended claims are intended to cover all such modificationsand embodiments which come within the spirit and scope of the presentinvention.

What is claimed is:
 1. A device for attaching a fixation element tobone, comprising: a longitudinal member extending along a longitudinalaxis from a proximal end to a distal end and having a channel extendingtherein adapted for receiving at least a portion of one fixationelement; and a shaft positioned coaxially within and extending along atleast a portion of the longitudinal member, at least a portion of theshaft retained within the channel of the longitudinal member and havinga distal end configured and adapted to contact at least a portion of thefixation element, a spring positioned adjacent the shaft for resilientlybiasing the shaft in an axial direction, wherein the shaft is moveablewith respect to the longitudinal member to drive the fixation elementinto bone.
 2. The device of claim 1, further comprising an adjustmentgauge for adjusting the bias of the spring.
 3. The device of claim 1,wherein the shaft is moveable from a loaded position to a unloadedposition.
 4. The device of claim 3, further comprising a lockingmechanism for engaging the shaft, wherein the locking mechanism ismoveable from a first position to a second position, and when thelocking mechanism is in the first position the shaft is locked in theloaded position and when the shaft is in the second position the shaftis moveable to the second unloaded position.
 5. The device of claim 4,wherein the locking mechanism is pivotally mounted to the longitudinalmember and is resiliently biased into the locking position.
 6. Thedevice of claim 3, further comprising a loading mechanism for engagingthe shaft and moving the shaft from the unloaded to the loaded position.7. The device of claim 6, wherein the loading mechanism comprises aslide member moveably mounted to the longitudinal member that isoperable by a user to manually move the shaft in an axial direction. 8.The device of claim 7, wherein the slide member is resiliently biasedout of engagement with the shaft.
 9. The device of claim 3, wherein theshaft is moveable to the loaded position by applying force on the distalend of the device.
 10. The device of claim 6, further comprising atleast one pin member rigidly mounted tot he shaft and extending radiallytherefrom, and wherein the loading mechanism comprises a cam mechanismthat has an internal ramp for engaging the pin and moving the shaft inthe axial direction.